This is such an interesting topic. yes, i believe they do stay in chrysalis and that they can somehow sense the weather outside is not favorable. It is just amazing. I am in north Texas where we had pretty mild temps for most of the summer and I had swallowtails emerging pretty regularly. Now that we have had two solid weeks of temps at 107 I noticed that none of my chrysalids have emerged. Nature is so incredible. A couple of months ago I had a giant swallowtail emerge and fly off. Later that afternoon I saw what I am pretty sure was the same bfly come back into my yard and get up underneath a crepe myrtle. He was hanging on for the longest time not going anywhere, when all of the sudden a wild wind and rain storm blew through. So he sensed it was coming and sought shelter long before we saw it. I love this stuff!! :-)